At this time of increased public interest in reducing the use of chemical additives, it is relevant to consider natural alternatives for antimicrobial agents used e.g. for preserving foods and cosmetics, as disinfectants, and as an antimicrobial ingredient of detergent and cleaning compositions. This has increased interest in preservation using live bacterial cultures (Jeppesen & Huss 1993) and enzymes like lactoperoxidase (Farrag & Marth 1992), glucose oxidase (Jeong et al. 1992) and lysozyme (Johansen et al. 1994).
Gram-negative bacteria are often resistant to a large number of harmful agents due to the effective permeability barrier function of the outer membrane (Nakae 1985). However, certain cationic peptides or polymers are under certain conditions apparently able to traverse the outer membrane of Gram-negative bacteria (Vaara 1992, Vaara & Vaara 1983), probably as a result of their binding to the anionic lipopolysaccharide-covered surface of the Gram-negative cell. The mechanism of the antibacterial action of basic peptides is not known, but it has been suggested that small or short cationic polymers can form a channel in the cytoplasmic membrane, thus uncoupling electron transport and causing leakage (Christensen et al. 1988; Hugo 1978; Kagan et al. 1990). It has also been proposed that they induce autolysis due to activation of the autolytic enzymes (Bierbaum & Sahl 1991). The larger or longer cationic basic polymers agglutinate the cells and may thereby inhibit growth.
Thus, the object of invention is co provide a method of killing or inhibiting microbial cells which is easy to use, relatively inexpensive, and more effective than the known disinfecting preserving methods.